<template>
<div class="index" v-loading.fullscreen.lock="fullscreenLoading" element-loading-text="拼命加载中...">
  <input type="file" @change="importFile(this)" id="imFile" style="display: none"
     accept="application/vnd.openxmlformats-officedocument.spreadsheetml.sheet, application/vnd.ms-excel"/>
  <a id="downlink"></a>
  <el-button class="button" @click="uploadFile()">导入</el-button>
  <el-button class="button" @click="downloadFile(excelData)">导出</el-button>
  <!--错误信息提示-->
  <el-dialog title="提示" v-model="errorDialog" size="tiny">
<span>{{errorMsg}}</span>
  <span slot="footer" class="dialog-footer">
    <el-button type="primary" @click="errorDialog=false">确认</el-button>
  </span>
  </el-dialog>
  <!--展示导入信息-->
  <el-table :data="excelData" tooltip-effect="dark">
<el-table-column label="名称" prop="name" show-overflow-tooltip></el-table-column>
<el-table-column label="分量" prop="size" show-overflow-tooltip></el-table-column>
<el-table-column label="口味" prop="taste" show-overflow-tooltip></el-table-column>
<el-table-column label="单价(元)" prop="price" show-overflow-tooltip></el-table-column>
<el-table-column label="剩余(份)" prop="remain" show-overflow-tooltip></el-table-column>
  </el-table>
</div>
</template>

<script>
// 引入xlsx
let XLSX = require('xlsx')
export default {
  name: 'Index',
  data () {
    return {
      fullscreenLoading: false, // 加载中
      imFile: '', // 导入文件el
      outFile: '', // 导出文件el
      errorDialog: false, // 错误信息弹窗
      errorMsg: '', // 错误信息内容
      excelData: [ // 测试数据
        {
          name: '红烧鱼', size: '大', taste: '微辣', price: '40', remain: '100',
        },
        {
          name: '麻辣小龙虾', size: '大', taste: '麻辣', price: '138', remain: '200',
        },
        {
          name: '清蒸小龙虾', size: '大', taste: '清淡', price: '138', remain: '200',
        },
        {
          name: '香辣小龙虾', size: '大', taste: '特辣', price: '138', remain: '200',
        },
        {
          name: '十三香小龙虾', size: '大', taste: '中辣', price: '138', remain: '108',
        },
        {
          name: '蒜蓉小龙虾', size: '大', taste: '中辣', price: '138', remain: '100',
        },
        {
          name: '凉拌牛肉', size: '中', taste: '中辣', price: '48', remain: '60',
        },
        {
          name: '虾仁寿司', size: '大', taste: '清淡', price: '29', remain: '无限',
        },
        {
          name: '海苔寿司', size: '大', taste: '微辣', price: '26', remain: '无限',
        },
        {
          name: '金针菇寿司', size: '大', taste: '清淡', price: '23', remain: '无限',
        },
        {
          name: '泡菜寿司', size: '大', taste: '微辣', price: '24', remain: '无限',
        },
        {
          name: '鳗鱼寿司', size: '大', taste: '清淡', price: '28', remain: '无限',
        },
        {
          name: '肉松寿司', size: '大', taste: '清淡', price: '22', remain: '无限',
        },
        {
          name: '三文鱼寿司', size: '大', taste: '清淡', price: '30', remain: '无限',
        },
        {
          name: '蛋黄寿司', size: '大', taste: '清淡', price: '20', remain: '无限',
        },
      ],
    }
  },
  mounted () {
    this.imFile = document.getElementById('imFile')
    this.outFile = document.getElementById('downlink')
  },
  methods: {
    uploadFile: function () { // 点击导入按钮
      this.imFile.click()
    },
    downloadFile: function (rs) { // 点击导出按钮
      let data = [{} ]
      for (let k in rs[0]) {
        data[0][k] = k
      }
      data = data.concat(rs)
      this.downloadExl(data, '菜单')
    },
    importFile: function () { // 导入excel
      this.fullscreenLoading = true
      let obj = this.imFile
      if (!obj.files) {
        this.fullscreenLoading = false
        return
      }
      let f = obj.files[0]
      let reader = new FileReader()
      let $t = this
      reader.onload = function (e) {
        let data = e.target.result
        if ($t.rABS) {
          $t.wb = XLSX.read(btoa(this.fixdata(data)), { // 手动转化
            type: 'base64',
          })
        } else {
          $t.wb = XLSX.read(data, {
            type: 'binary',
          })
        }
        let json = XLSX.utils.sheet_to_json($t.wb.Sheets[$t.wb.SheetNames[0]])
        $t.dealFile($t.analyzeData(json)) // analyzeData: 解析导入数据
      }
      if (this.rABS) {
        reader.readAsArrayBuffer(f)
      } else {
        reader.readAsBinaryString(f)
      }
    },
    downloadExl: function (json, downName, type) { // 导出到excel
      let keyMap = [] // 获取键
      for (let k in json[0]) {
        keyMap.push(k)
      }
      // console.info('keyMap', keyMap, json)
      let tmpdata = [] // 用来保存转换好的json
      json.map((v, i) => keyMap.map((k, j) => Object.assign({}, {
        v: v[k],
        position: (j > 25 ? this.getCharCol(j) : String.fromCharCode(65 + j)) + (i + 1),
      }))).reduce((prev, next) => prev.concat(next)).forEach(function (v) {
        tmpdata[v.position] = {
          v: v.v,
        }
      })
      let outputPos = Object.keys(tmpdata) // 设置区域,比如表格从A1到D10
      let tmpWB = {
        SheetNames: ['mySheet' ], // 保存的表标题
        Sheets: {
          'mySheet': Object.assign({},
            tmpdata, // 内容
            {
              '!ref': outputPos[0] + ':' + outputPos[outputPos.length - 1], // 设置填充区域
            }),
        },
      }
      let tmpDown = new Blob([this.s2ab(XLSX.write(tmpWB,
        { bookType: (type === undefined ? 'xlsx' : type), bookSST: false, type: 'binary' } // 这里的数据是用来定义导出的格式类型
      )) ], {
        type: '',
      }) // 创建二进制对象写入转换好的字节流
      let href = URL.createObjectURL(tmpDown) // 创建对象超链接
      this.outFile.download = downName + '.xlsx' // 下载名称
      this.outFile.href = href // 绑定a标签
      this.outFile.click() // 模拟点击实现下载
      setTimeout(function () { // 延时释放
        URL.revokeObjectURL(tmpDown) // 用URL.revokeObjectURL()来释放这个object URL
      }, 100)
    },
    analyzeData: function (data) { // 此处可以解析导入数据
      return data
    },
    dealFile: function (data) { // 处理导入的数据
      this.imFile.value = ''
      this.fullscreenLoading = false
      if (data.length <= 0) {
        this.errorDialog = true
        this.errorMsg = '请导入正确信息'
      } else {
        this.excelData = data
      }
    },
    s2ab: function (s) { // 字符串转字符流
      let buf = new ArrayBuffer(s.length)
      let view = new Uint8Array(buf)
      for (let i = 0; i !== s.length; ++i) {
        view[i] = s.charCodeAt(i) & 0xFF
      }
      return buf
    },
    getCharCol: function (n) { // 将指定的自然数转换为26进制表示。映射关系：[0-25] -> [A-Z]。
      let s = ''
      let m = 0
      while (n > 0) {
        m = n % 26 + 1
        s = String.fromCharCode(m + 64) + s
        n = (n - m) / 26
      }
      return s
    },
    fixdata: function (data) { // 文件流转BinaryString
      let o = ''
      let l = 0
      let w = 10240
      for (; l < data.byteLength / w; ++l) {
        o += String.fromCharCode.apply(null, new Uint8Array(data.slice(l * w, l * w + w)))
      }
      o += String.fromCharCode.apply(null, new Uint8Array(data.slice(l * w)))
      return o
    },
  },
}
</script>
